Printed in Sweden Copyri,qht @ 1977 by Academic Press, Inc. in any form reserved A// rights of reproduction lS.7.V 0014-4827
Experimental
EVIDENCE
Cell Research 110 (1977)33l-335
FOR PREFORMED
TMP SYNTHETASE M. S. DICKENS,’
mRNA IN THE INDUCTION
IN TETRAHYMENA J. LUCAS-LENARD
OF
PYRIFORMIS
and J. S. ROTH2
Biological Sciences Group, Section of Biochemistry and Biophysics, University of Connecticut, Storrs, CT 06268, USA
SUMMARY The induction of thymidylate (TMP) synthetase in Tetrahymena pyriformis occurred following a shift from complex medium to defined medium, or following addition of cyclic guanosine-3’,5’monophosphate (cGMP) to complex medium. Inhibitors of macromolecular synthesis were used to probe the role of culture conditions in the enzyme induction. In defined medium actinomycin D minimally decreased the induction of enzyme activity, implying that control of enzyme synthesis is not exerted at the transcriptional level. Cycloheximide markedly inhibited the induction of TMP synthetase by defined medium, suggesting the requirement for protein synthesis in the induction process. In contrast, in complex medium where the activity of the synthetase was low (spec. act.
Experimental
EVIDENCE
Cell Research 110 (1977)33l-335
FOR PREFORMED
TMP SYNTHETASE M. S. DICKENS,’
mRNA IN THE INDUCTION
IN TETRAHYMENA J. LUCAS-LENARD
OF
PYRIFORMIS
and J. S. ROTH2
Biological Sciences Group, Section of Biochemistry and Biophysics, University of Connecticut, Storrs, CT 06268, USA
SUMMARY The induction of thymidylate (TMP) synthetase in Tetrahymena pyriformis occurred following a shift from complex medium to defined medium, or following addition of cyclic guanosine-3’,5’monophosphate (cGMP) to complex medium. Inhibitors of macromolecular synthesis were used to probe the role of culture conditions in the enzyme induction. In defined medium actinomycin D minimally decreased the induction of enzyme activity, implying that control of enzyme synthesis is not exerted at the transcriptional level. Cycloheximide markedly inhibited the induction of TMP synthetase by defined medium, suggesting the requirement for protein synthesis in the induction process. In contrast, in complex medium where the activity of the synthetase was low (spec. act.
